Bumper system with face-mounted energy absorber

ABSTRACT

A bumper includes a beam and an energy absorber supported thereon. The energy absorber includes horizontal walls, each having a front portion, a rear portion, and an interconnecting mid-portion that offsets and misaligns the front and rear portions. Upon impact, the front and rear portions collapse with the offset mid portion wrapping back upon itself with a predictable energy-absorbing collapse. The energy absorber further includes flanges and friction pads that frictionally engage the top and bottom of the beam to temporarily retain the energy absorber to the beam. In one embodiment, the front beam wall includes at least one aperture, and the energy absorber includes a tubular column extending from its front wall through the aperture in the front beam wall to the rear beam wall. By this arrangement, the front wall of the energy absorber receives support from the front beam wall via the structural column.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.10/061,670, filed Feb. 1, 2002 now U.S. Pat. No. 6,609,740, entitledBUMPER SYSTEM WITH FACE-MOUNTED ENERGY ABSORBER, which in turn claimsbenefit under 35 U.S.C. 119(e) of a provisional application Ser. No.60/283,969, filed Apr. 16, 2001, entitled BUMPER SYSTEM WITHFACE-MOUNTED ENERGY ABSORBER. This application is further acontinuation-in-part of application Ser. No. 09/967,196, filed Sep. 28,2001 now U. S. Pat. No. 6575510, entitled BUMPER SYSTEM WITHFACE-ABUTTING ENERGY ABSORBER, which in turn claims benefit ofprovisional application Ser. No. 60/284,058, filed Apr. 16, 2001,entitled BUMPER SYSTEM WITH FACE-ABUTTING ENERGY ABSORBER under 35 USC§119.

BACKGROUND OF THE PRESENT INVENTION

The present invention relates to automotive bumper systems having beamsand energy absorbers located on faces of the beams.

Many vehicle designs use energy absorbers positioned on a face or frontsurface of a steel bumper beam to improve energy absorption of a bumpersystem. The energy absorbers provide an initial level of energyabsorption for low impact, including reducing damage during low impact,and also provide a supplemental level of energy absorption during highimpact (i.e. before and at the time that the beam and vehicle begin toabsorb substantial amounts of energy). Usually, the energy absorbers arefastened to the bumper beam with fasteners that assure accuratepositioning of the energy absorber on the beam. The reasoning includesaccurately positioning the energy absorber on the bumper beam to assureconsistent performance, as well as to assure accurate positioning foraesthetics and assembly (e.g. to assure a good fit of the front-endfascia over the energy absorber and beam during assembly).

However, improvements are desired in terms of temporary and permanentattachment, and for improved and more reliable energy absorption.Typically, attachment of the energy absorber to bumper beams requires aplurality of mechanical fasteners. This is disadvantageous sincemechanical fasteners require manual labor to install, which can addundesirably to cost. Also, the mechanical fasteners can result inlocalized and non-uniform stress distribution during impact, resultingin inconsistent collapse of the bumper system and poor energy absorptionon impact. Further, fixing the energy absorber to the beams results inan inability of the energy absorber to shift and adjust tonon-perpendicular and uneven loads transmitted from the impactingbodies. At the same time, depending on the bumper system, sometimesshifting of an energy absorber is not good since it can result inunpredictable, premature and non-uniform collapse, resulting in poor orinconsistent energy absorption by the bumper system.

Improvement is also desired for corner impact structure on bumpersystems. Many existing bumper systems require that a front surface of anend of a bumper beam be shaped at an increased angle relative to thefront of rest of the bumper beam to match an aerodynamic curvature ofthe vehicle at its front fender. One way to achieve this is by mitercutting an end of the bumper beam at an angle, and thereafter welding aplate onto the angled end to form a compound-angled flat front surfacefor supporting an energy absorber such as a foam cushion. Another way isto deform or crush an end of the bumper beam to form an angled frontsurface. Yet another way is to weld a bracket onto an end of the bumperbeam, with the bracket extending longitudinally beyond the bumper beamto form the desired shape. However, all of these alternatives havedrawbacks. For example, they each require a secondary operation, resultin increased dimensional variation, and require significant investmentin capital equipment. Further, they can lead to increased scrap, asubstantial increase in manpower and manufacturing time, and substantialincrease in inventories and work in process.

For all of the above reasons, there is a desire for bumper systems thatyield a better, more consistent, more reliable, and greater impactenergy absorption, both for low and high impact events, and also forsquare and skewed impact directions. Also, there is a desire forimprovements facilitating assembly of an energy absorber to a beam, withlower cost and fewer parts, and with less labor. Still further, there isa desire for energy absorber designs that allows adjustment and tuningfor optimal front end and corner impact strengths, even late in thebumper development program, and yet that do not require expensive orcomplex molding techniques or assembly techniques nor secondary mitercutting or crush forming bumper end sections. Still further, there is adesire for energy absorber designs that are adaptable for use with manydifferent bumper beam cross-sectional shapes and sizes. Also, energyabsorber designs are desired that are flexible and usable on non-linearbumper beams having different curvatures and longitudinal sweeps, andhaving different cross sections.

SUMMARY OF THE PRESENT INVENTION

In one aspect of the present invention, a bumper system for a passengervehicle includes a beam having a face and adapted for attachment to avehicle frame, and an energy absorber supported against the face of thebeam. The energy absorber includes longitudinally-extending top andbottom horizontal walls. At least part of one of the top and bottomhorizontal walls includes a front portion, a rear portion extendingparallel the front portion, and an offset mid-portion that interconnectsthe front and rear portions but that offsets and misaligns the front andrear portions. By this arrangement, upon a frontal impact, the front andrear portions telescopingly collapse with the offset mid portionwrapping back upon itself with a predictable energy-absorbing collapse.

In another aspect of the present invention, a bumper system for apassenger vehicle includes a beam having a face and top and bottom beamwalls and being adapted for attachment to a vehicle frame, and an energyabsorber supported against the face of the beam. The energy absorberincludes a plurality of horizontally-and-longitudinally-extending topand bottom walls that generally align with the top and bottom beamwalls, and further includes flanges that overlap onto the top and bottombeam walls and that include at least a pair of fingertip-like frictionpads that frictionally engage the top and bottom beam walls totemporarily retain the energy absorber to the beam.

In yet another aspect of the present invention, a bumper system for apassenger includes a beam having front and rear beam walls, and that isadapted for attachment to a vehicle frame. The front beam wall includesat least one aperture in the front beam wall, with the rear beam wallincluding a support area located behind and spaced from the at least oneaperture. An energy absorber is supported against the front beam wall,and includes a plurality of horizontally-extendinglongitudinally-extending top and bottom walls and further includes frontand rear walls. The energy absorber walls includes at least onestructural column extending from the front wall through the rear walland through the at least one aperture in the front beam wall to alocation near the support area on the rear beam wall. By thisarrangement, the front wall of the energy absorber receives support fromthe front beam wall via the structural column.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a bumper system of the presentinvention, including a bumper tubular beam and an energy absorber on aface of the bumper beam;

FIG. 2 is a rear perspective view of the energy absorber of FIG. 1;

FIG. 3 is an enlargement of the circled area III in FIG. 1;

FIGS. 4-6 are cross-sectional views of the bumper system of FIG. 1, FIG.4 being before impact, FIG. 4A being similar to FIG. 4 but showing thestructure needed to avoid die lock during molding, FIG. 5 being at atime of low impact, and FIG. 6 being at a time of high impact,respectively;

FIGS. 7-7B are fragmentary top views of a prior art bumper system, FIG.7 showing a bumper beam including an angled miter cut (in dashed lines),FIG. 7A showing a plate welded onto the angled end of the bumper beam,and FIG. 7B showing a foam energy absorber on the bumper beam;

FIG. 8 is a perspective view of another bumper system including a bumperbeam and an energy absorber with rearward projections extending throughholes in a front surface of the bumper beam;

FIG. 9 is a cross sectional view taken along line IX—IX in FIG. 8;

FIG. 10 is a front perspective view of a bumper system including thebumper beam and the energy absorber;

FIG. 11 is a rear perspective view of the energy absorber of FIG. 10;and

FIGS. 12-14 are front, top and bottom views of the energy absorber ofFIG. 11, and FIG. 15 is an enlarged view of the right half of FIG. 12;

FIG. 12A is a front view like FIG. 12, but with a front face of theenergy absorber shaded to better show the “box-shaped” areas on theenergy absorber;

FIGS. 16-20, 22, 24, and 25 are cross sections along the lines XVI—XVIthrough XX—XX, XXII—XXII, XXIV—XXIV, and XXV—XXV in FIG. 15; and

FIGS. 21 and 23 are views similar to FIGS. 20 and 22, but after beingdeformed after impact.

FIGS. 26 and 27 are fragmentary perspective views of a bumper system ofthe present invention, including a bumper beam and an energy absorber;

FIGS. 28-31 are cross-sectional views of the energy absorber taken alongthe lines III—III, IV—IV, V—V, and VI—VI in FIG. 27; and

FIGS. 32 and 33 are front and rear perspective views of the energyabsorber shown in FIG. 2, and FIG. 33A is a fragmentary perspective viewof a portion of FIG. 33.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is described as utilizing a B-shaped double-tubebumper beam that is rollformed and swept. The present B-shaped bumperbeam is sufficiently described herein for a person skilled in the art tounderstand and practice the present invention, but it is noted that theprocess and method of making the illustrated B-shaped bumper beam isdescribed in greater detail in Sturrus patent U.S. Pat. No. 5,454,504,if the reader desires such information. It is specifically contemplatedthat the present invention could be used in combination with a bumperbeam having a shallower channel instead of the deep channel illustrated.For example, it is contemplated that the present invention could be madeto work on a D-shaped bumper where the bumper beam had a channelextending significantly into a front face of the bumper beam but wherethe channel does not extend completely to a rear wall of the bumperbeam. On the merits, the teachings of U.S. Pat. No. 5,454,504 areincorporated herein in its entirety for the purpose of providing acomplete disclosure of the entire bumper system.

Bumper system 20 (FIG. 1) includes a bumper beam 21 attached to avehicle, and an energy absorber 22 attached to a face of the bumper beam21. The illustrated bumper beam 21 is attached by brackets 20A. Crushtowers can also be used to mount the bumper beam. The illustrated beamis rollformed and swept (see Sturrus patent U.S. Pat. No. 5,454,504) andhas a continuous B-shaped double-tubular cross section (FIG. 3). Thedouble tubes are spaced vertically apart and include top and bottommid-walls 23 and 24 defining a longitudinally-extending channel 25 alongits front surface. A polymeric energy absorber 22 has a length withmultiple top and bottom box-shaped sections 27 and 27′ (not all beingthe same size or length) that abut the front surface 26 of the bumperbeam 21. The energy absorber 22 further includes a plurality ofrearwardly-extending nose sections 28 that extend into the channel 25.The nose sections 28 are trapezoidally-shaped to fit mateably into thechannel 25, and extend about 50% to 60% of the way to a bottom of thechannel 25. Where desired, the nose sections 28 include detents or areshaped to provide sufficient frictional engagement to temporarily retainthe energy absorber 22 on the bumper beam 21. The illustrated nosesections 28 include collapse-controlling kick walls 30 and 31 that liealong and abut the top and bottom mid-walls 23 and 24 of the bumper beam21. The kick walls 30 and 31 are non-parallel and are connected to thebox-shaped sections 27 and 27′ so that, upon impact by an object againstthe bumper system, the kick walls 30 and 31 bend in a predictable andpreplanned manner and press into the top and bottom mid-walls 23 and 24.During high impact (see FIGS. 3 and 4), the kick walls 30 and 31 presswith increasing force, resulting in a more consistent and controlledflexure and collapse of the box-shaped sections 27 of the polymericenergy absorber 22 and of the tube sections of the metal bumper beam 21as a system. The nose sections 28 are trapped within the channel 25,which eliminates the problem of the energy absorber sliding verticallyoff a face of the bumper beam (which is a problem in some bumper systemsusing an energy absorber mounted to a face of a bumper beam).

The B-shaped section of the bumper beam 21 includes, in addition to topand bottom mid-walls 23 and 24, a top wall 34, a front upper wall 35, abottom wall 36, a front lower wall 37, a rearmost rear wall 38 and achannel-forming rear wall 39. The top tube of the bumper beam 21 isformed by the walls 23, 34, 35, and 38. The bottom tube of the bumperbeam 21 is formed by the walls 24, 36, 37, and 38. The top and bottomtubes are interconnected by rear walls 38 and 39. Each of these walls23-24 and 34-39 can be flat or non-flat. For example, in some bumpersystems (such as the illustrated walls 23-24), it has been found to bebeneficial to make the horizontal walls 23, 24, 34, and 36 slightly bentor curved, both for purposes of providing a bumper beam that is lesslikely to prematurely kink and more likely to reliably and consistentlybend, but also for the purpose of ease of manufacture of the bumperbeam. As illustrated, the mid-walls 23 and 24 include front portionsthat are angled to created a tapered throat into which the nose sections28 of the energy absorber 22 tend to move upon impact. The mid-walls 23and 24 also include relatively flat rear portions that are generallyparallel. It is noted that, upon a low force impact, the energy absorber22 may move partially into this throat (see FIGS. 4-6) and, ifsufficient energy is absorbed during the low energy impact, may returnto an original shape without substantial deformation or damage to thevehicle or the bumper system.

The energy absorber 22 (FIG. 3) is a molded component of non-foampolymer, such as a blend of PC/ABS/PBT. For example, it is contemplatedthat General Electric's XENOY polymer will work for this purpose. Asnoted above, the energy absorber 22 includes top and bottom box-shapedsections 27 and 27 that abut a front of the front walls 35 and 37. Thetop box-shaped sections 27 engaging the top front wall 35 can be shapedslightly different than the bottom box-shaped sections 27′ that engagethe bottom front wall 37, if desired, but in the presently disclosedpreferred embodiment, they are similar in size and shape to betterassure a uniform and balanced collapse upon impact. The top box-shapedsections 27 include a front wall 41, open rear area 42, top wall 43 andbottom wall 44, as well as end walls 45 and 46 that tie the walls 41,43-44 together. The bottom box-shaped sections 27′ include similar walls41′-46′. Walls 46A, 46B, and 46C extend between and interconnect the topand bottom box-shaped sections 27 and 27′. It is noted that the top andbottom walls 43, 44, 43′, and 44′, when viewed from a position in frontof the bumper system, can be wavy or otherwise non-linear and non-flatin shape. This provides the top and bottom walls 43, 44, 43′, and 44with increased strength for resisting buckling, and also helps eliminatedistortions such as snaking that occur when molding a long part. It isalso noted that the surfaces defined by the front walls and rear areas41, 42, 41′, and 42′ (and potentially the top and bottom walls 43, 44,43′ and 44′) are discontinuous and further include apertures to preventdie lock when molding. (i.e. They include apertures to allow moldtooling to pass through the plane of one wall to form another wall.) Ina preferred form, the apertures are sufficient in size so that themolding dies do not require slides or pulls. In other words, the energyabsorber 22 can be made by using hard male and female molds, neither ofwhich require secondary movable die components for creating blindsurfaces.

The nose sections 28 (FIG. 4) include kick walls 30 and 31, and furtherinclude a connector wall 48 that interconnects the leading (rear-most)ends of the kick walls 30 and 31. The connector wall 48 is locatedhalfway into channel 25 so that it acts as a guide during impact toguide the leading ends of the kick walls 30 and 31 into the channel 25.Specifically, the connector wall 48 is positioned about 30% to 80% ofthe way into the channel 25, or more particularly about 50% to 60% intothe channel 25. This results in the energy absorber 22 being able toabsorb significant energy, such as may be incurred in a low energyimpact. Specifically, in a low energy impact (FIG. 4), the energyabsorber 22 absorbs a majority of the energy of the impact energy, andthe energy absorber 22 and the bumper beam 21 do not permanently deform.In an intermediate energy impact (FIG. 5), the energy absorber 22deforms substantially, potentially taking on a permanent deformation.However, the bumper beam 21 deflects and absorbs energy, but themid-walls 23 and 24 only temporarily flex and do not permanently deform.In a high-energy impact (see FIG. 6), the kick walls 30 and 31 cause themid-walls 23 and 24 to buckle as they approach a maximum amount ofdeflection. Both the energy absorber 22 and the bumper beam 21permanently deform. The point of buckling is designed into the bumpersystem 20 to cause a two-step collapse (FIGS. 5-6) so that a maximumamount of energy is absorbed without damaging the vehicle, whileconsidering all relevant factors such as preferred de-accelerations,occupant safety, government standards, and the like.

The top kick wall 30 (FIG. 4)includes a root region 50 that connects tothe bottom wall 44 of the top box section 27, and the bottom kick wall31 includes a root region 51 that connects to the top wall 43′ of thebottom box section 27′. This direct connection allows the nose section28 to react quickly and directly to an impact, because the impact energyis transferred directly through the bottom wall 44 of the box section 27to the kick wall 30, and because the impact energy is transferreddirectly through the top wall 43′ of the bottom box section 27′ to thekick wall 31. Due to walls 42, the natural flow of material at 50 and 51during impact cause the material to move into walls 30 and 31 alongdirections A and B, respectively (see FIG. 5).

A top flange 53 (FIG. 4) extends rearwardly from the top box section 27,and a bottom flange 54 extends rearwardly from the bottom box section27′. The flanges 53 and 54 engage top and bottom surfaces on the bumperbeam 21. Optionally, the flanges 53 and 54 can include attachment tabsor hooks for engaging apertures or features in the bumper beam 21 forretaining (temporarily or permanently) to the bumper beam 21. Theillustrated flanges 53 and 54 include fingertip-like pads 53′ and 54′that frictionally engage top and bottom surfaces of the bumper beam 21.These frictional flanges 53 and 54 are advantageous in that all (ormost) fasteners can be eliminated. It is also noted that hooks mayextend through holes in the faces 35 and 37 of the bumper beam 21 andretain the energy absorber 22 on the beam 21.

It is noted that the present arrangement (see FIGS. 3 and 4-6)“reverses” the B-shaped cross section of the bumper beam 21 relative tothe vehicle that it is attached to, which creates a usable energyabsorbing crush space within the channel of the bumper beam 21.Previously, B-shaped bumper beams were typically used with the flat sideof the B shape facing forwardly and supporting the energy absorber.However, with the flat side of the B shape facing forwardly, the knownenergy absorbers can only collapse against the flat side. Thus, energyabsorption is more limited than in the present design. Specifically, thepresent arrangement of FIGS. 4-6 provides for a more controlled andpredictable two-stage energy absorption upon impact, because the energyabsorber kick walls 30 and 31 stabilize the walls 23 and 24 of thebumper beam 21 during initial impact. Further, the arrangement causesthe nose section 28 to slide into the channel of the bumper beam 21,providing an intermediate step of energy absorption, which helps inreading sensor outputs for sensing impacts, such as are used for air bagdeployment. Still further, it is believed to be novel to utilize wallstructure in an energy absorber to “kick” out and cause predictablecollapse of a steel bumper beam (see FIG. 6), as in the presentinvention described above.

It is contemplated that corner sections can be molded onto ends of theenergy absorber 22 or integrally formed as part of the energy absorber.Advantageously, the corner sections can be specifically designed tosatisfy a variety of functional and aesthetic conditions. For example,the corner sections can be square-shaped and can be molded with anyamount of wall thickness and ribs desired, such that substantiallyincreased amount of corner impact loading can be successfully dissipatedby the corner section. Alternatively, a different polymeric material canbe molded onto ends of the energy absorber to create the corner section,such as a glass reinforced stiffer polymeric material.

FIGS. 8-9 show a bumper system 200 including a D-shaped single-tubebumper beam 201 supported on mounting towers 202, and an energy absorber203 that functions similar to the bumper beam 20 and energy absorber 21discussed above. The bumper beam 201 includes two spaced apertures 204in its front surface 205, and the energy absorber 203 includesrearwardly projecting nose sections 206 that project through theapertures 204 and that extend to the rear wall 207 of the bumper beam201. The illustrated nose sections 206 abut the rear wall 207, but it isnoted that they can terminate short of the rear wall 207 to provide astepped crush stroke that provides different levels of energy absorptionat different impact stroke depths. It is contemplated that more or lessapertures 204 and nose sections 206 can be used. During a vehicleimpact, the nose sections 206 provide an initial level of impactstrength and energy absorption. As the impact stroke increases, the nosesections 206 buckle outwardly, and engage top and bottom walls of thebumper beam 201. An advantage of the bumper system 200 is that itprovides good localized control and a consistent and repeatable energyabsorption over energy absorption during impact.

Prior art (FIGS. 7-7B) includes a B-shaped bumper beam 221, miter cut atan angle along a line 222, with a flat plate 223 welded onto the cut endto provide an extended flat front surface having an increased angle atthe miter cut end. A foam energy absorber 224 is positioned against theflat front surface of the bumper beam 221, and extends onto the flatplate 223. The arrangement below eliminates the need to miter cut endsof a bumper beam, which is advantageous because miter cutting is anexpensive secondary operation that takes time, money, equipment, andresults in increased inventories. The invention described beloweliminates the miter cutting and secondary operations needed in thebumper system 221/222.

MODIFICATION

Bumper system 100 (FIG. 10) includes a B-shaped bumper beam 101 and anenergy absorber 102 attached to the beam's “flat” front face. The energyabsorber 102 incorporates box-shaped sections similar to the concept ofthe energy absorber 22 previously described, but does so in a mannerpermitting the energy absorber 102 to be used on the “flat” side of theB-shaped bumper beam 101 (i.e. the side of the B-shaped bumper beam 101that does not have a channel formed in it (see FIGS. 18 and 20)), asdescribed below. Also, the energy absorber 102 can be used on a D-shapedor single tube bumper beam.

The bumper beam 101 has the same shape and walls as the bumper beam 21,except that the bumper beam 101 has an opposite longitudinal curvaturefor matching an aerodynamically-shaped curved front of a vehicle. In thebeam 101, the longitudinal curvature places the “flat” surface 103 (FIG.20) on a front side of the bumper beam 101, and the two tube sections104 and 105 and the channel 106 therebetween on a rear side of the beam101. Two mounting brackets or plates 107 and 108 (FIG. 10) are attachedto the tube sections 104 and 105. The mounting plates 107 and 108 eachhave a flat plate section 109 that engages and is welded to a back sideof the tube sections 104 and 105. A section 110 (FIG. 13) extends fromthe mounting plates 107 and 108 at a location about 1 inch to 1½ inchesfrom an end of the tube sections 104 and 105. The sections 110 eachinclude an outer leg 112 that extends rearward of the plate section 109,generally at a corner of the vehicle. It is contemplated that themounting plates 107 and 108 can have a forward loop 111 that partiallycovers an end surface of the energy absorber if desired (see FIG. 25).Coplanar flanges 113 and 114 (FIG. 13) extend from the rear/outer endsof the brackets 107 and 108. It is noted that other mounting systems canbe used for vehicle attachment on the present bumper system if desired.

The energy absorber 102 is symmetrical about a centerline 115 (FIG.12A), with each half of the energy absorber 102 including fourbox-shaped sections 117-120, each being interconnected bylongitudinally-extending walls, as described below. The box-shapedsection 117 (FIG. 12A) is adjacent the centerline 115 and includes afront face wall 121, a top wall 122, a bottom wall 123, an inboardsidewall 124 and an outboard sidewall 125. A rear of the box-shapedsection 117 is open and the walls 122-125 have draft angles, so that thebox-shaped section 117 can be formed on molding dies that do not requiredie pulls or other moving parts for forming blind surfaces. Two large“crush-initiator” apertures 126 (FIG. 15) are formed in the inboardsidewall 124 to weaken the box-shaped section 117, to provide for anoptimal crush stroke upon impact against the bumper system 100 andspecifically to provide for optimal energy absorption during the crushstoke. The illustrated apertures 126 are each about ⅓ of a total heightof the inboard sidewall 124 (see FIG. 18), are located at a top thirdand a bottom third of the sidewall 124, and extend to a full depth ofthe sidewall 124. Different shapes of apertures can be used. Theillustrated apertures 126 are not rectangular, but instead have at leastone curved edge 126′, which is designed to initiate a controlled crushduring an impact for optimal energy absorption during impact, and whichis also designed to facilitate molding. A strip of material between theapertures 126 and also the strips of material above and below theapertures 126 form the structure of sidewall 124. Apertures 127 (FIG.15) are also formed on the front face wall 121 as desired, such as toreduce mass, improve tooling, and provide clearances and attachments tofascia. The outboard sidewall 125 has a C-shaped profile (when viewed ina car-mounted position), and has a vertical center portion 128 that islocated closer to the centerline 115 than the upper and lower portions.A top angled portion 129 of the front face wall 121 slopes rearwardlyfrom a remainder of the vertical front face wall 121, which is morevertically oriented, but not perfectly vertical.

The box-shaped section 118 (FIG. 12A) is adjacent the box-shaped section117 and includes a front face wall 131, a top wall 132, a bottom wall133, an inboard sidewall 134 and an outboard sidewall 135. Thebox-shaped section 118 is about double a width of the box-shaped section117 (in a longitudinal direction), and the inboard sidewall 135 isC-shaped to a longitudinal width about double the dimension of theC-shape of the outboard sidewall 124 of the center box-shaped section117. Also, a top angled portion 139 of the front face wall 131 has avertical dimension that is slightly less than the top angled portion 129of the center box-shaped section 117, so that the combined front face ofthe energy absorber matches a shape of the fascia panel placed on it.The outboard sidewall 135 (FIG. 17) has three apertures 136 that aresimilar to the apertures 126 found in the sidewall 124 described above,with the exception that one of the apertures 136 is formed in each thirdof the outboard sidewall 135.

The box-shaped section 119 (FIG. 12A) is adjacent the box-shaped section118 and includes a front face wall 141, a top wall 142, a bottom wall143, an inboard sidewall 144 and an outboard sidewall 145. Thebox-shaped section 119 is about ⅔ of a width of the box-shaped section118 (in a longitudinal direction). The inboard and outboard sidewalls144 and 145 are relatively flat (i.e. are not C-shaped). Also, a topangled portion 149 of the front face wall 141 has a vertical dimensionthat is slightly less than the top angled portion 139 of the box-shapedsection 118, so that the combined front face of the energy absorbermatches a shape of the fascia panel placed on it. The inboard andoutboard sidewalls 144 and 145 each have two apertures 146 (FIG. 20)that are similar to the apertures 126 found in the sidewall 124described above, with the exception that the inboard sidewall 144 alsohas a center aperture 146.

The box-shaped section 120 (FIG. 12A) is adjacent the box-shaped section119 and includes a front face wall 151, a top wall 152, a bottom wall153, an inboard sidewall 154 and an outboard sidewall 155. Thebox-shaped section 120 is about equal in width to the box-shaped section117 (in a longitudinal direction). The inboard and outboard sidewalls154 and 155 are relatively flat (i.e. are not C-shaped). Also, the frontface wall 151 extends to a top of the box shaped section 120, and thereis not a top angled portion like the other box-shaped sections 117-119.The inboard sidewall 154 has two apertures 156 that are similar to theapertures 126 found in the sidewall 124 described above. The illustratedbox-shaped section 120 is actually divided into vertically-spaced-aparthalves, and consistent with that the front face wall 151 and also theinboard and outboard sidewalls 154 and 155 are actually divided into topand bottom halves, with the center section being entirely open exceptfor a vertical stabilizing rib 157.

The illustrated box-shaped sections 117-120 are connected together byinterconnecting “honeycomb-shaped” structures in the form of fourhorizontal ribs 160-163 (FIG. 12A) that are spaced equally apart in avertical direction. It is contemplated that the box-shaped sections117-120 can be connected together by different arrangements and stillincorporate many of the advantages of the present energy absorber. Thetop rib 160 and the bottom rib 163 extend continuously from end to endof the energy absorber 102. The middle two ribs 161 and 162 also extendend to end of the energy absorber 102, with the exception that themiddle ribs 161 and 162 are discontinued near the centerline 115 and donot connect the two center box-shaped sections 117. Also, the ribs 161and 162 connect the top and bottom legs of the C-shaped inner portion ofwalls 125 and 134. The box-shaped sections 117-120 are also connectedtogether by a rear wall 164. The rear wall 164 completely covers a rearof the energy absorber 102, with the exception that an opening is formedin the rear wall 164 at each of the box-shaped sections 117-120 tofacilitate tooling and prevent a die lock condition. The rear wall 164not only ties the sections 117-120 together, but also forms verticalstraps that tie the top and bottom walls together to prevent the top andbottom walls from spreading apart during an impact. This also eliminatesthe need for top and bottom fasteners.

A top flange 170 (FIG. 13) and a bottom flange 171 (FIG. 14) are formedon top and bottom edges of the rear wall 164. The flanges 170 and 171wrap onto tops and bottoms of the bumper beam 101. Fingertip-like pads172 are formed on the flanges 170 and 171 for engaging mating areas onthe top surface and on the bottom surface of the bumper beam 101 totemporarily frictionally retain the energy absorber 102 on the bumperbeam 101. Also, hooks 173 (FIGS. 10-11) are formed on tabs that extendfrom (and co-planar with) the top and bottom walls 122, 123, 132, 133,142, 143, 152, and 153. The hooks 173 are shaped to engage mating holesin a front face of the bumper beam 101. The hooks 173 (and also flanges53-54) provide an opportunity for “blind” snap-attachment, such as whenan operator has preassembled an energy absorber to a fascia, and thenattaches the assembled absorber/fascia as a unit to a vehicle front. Insuch event, the fascia prevents the operator from attaching the absorberto a bumper beam.

The energy absorber 102 (FIG. 11) includes integrally-formed endsections 180 and 181 that are symmetrically shaped and that areoptimally shaped to form end-located crush boxes for energy absorptionupon corner impact to a vehicle. The end sections 180 and 181 eachinclude a vertical rib 182 (FIG. 12A) that transversely crosses andconnects to the horizontal ribs 160-163 to form a honeycomb shape. Theoutboard sidewall 155 is extended rearwardly so that it substantiallycovers the open end of the tube sections on the bumper beam 101. Also,the rear wall 164 is extended at a location 164′ (FIGS. 22, 24, and 25)from the outboard sidewall 155 to form a rearwardly extending box 164″(FIG. 25) that fits adjacent an end of the bumper beam. It is noted thatthe mounting brackets 107 and 108 can include a forward loop 111 thatholds the box 164″ in place against an end of the bumper beam, ifdesired. A crescent-shaped flange 183 extends coplanar with the facefront walls 121, 131, 141, and 151. The flange 183 is stiff butflexible, such that it does a good job of supporting front-end fascia,such as RIM urethane fascia, placed on it. At the same time, the flange183 is flexible for flexing during a corner impact on a vehicle, thusreducing damage to the vehicle.

The illustrated top and bottom walls 122, 123, 132, 133, 142, 143, 152,and 153 are wave-shaped or corrugated in shape to facilitate molding andstrength. The illustrated walls of the box-shaped sections 117-120 andwalls 160-163 and adjacent areas are about 2 mm thick, while the wallsof the end sections 180 and 181 are about 3 to 4 mm thick. (CompareFIGS. 16-20 to the FIGS. 22-25.) However, it is contemplated that thewalls and thickness can be made any thickness, including localizedvariations made to optimize the energy absorption. Since the mold diesare relatively non-complex (since pulls and movable components formaking blind surfaces are not required), the walls can be made thickerrelatively easily by grinding away metal in the molding dies. Also, theapertures can be made smaller by grinding away metal, such that thecrush/impact strength can be closely and accurately controlled, and alsocan be carefully adjusted and tuned to react to the actual results ofvehicle crash testing during bumper development for a particular modelvehicle. For example, by reviewing the energy absorber 102 and bumperbeam 101 after an impact (compare FIGS. 20 and 22 which are beforeimpact, and FIGS. 21 and 23 which are after impact), intelligentdecisions can be made regarding what areas of the energy absorber 102require additional strength, and what areas need to be weakened. Forexample, by changing a shape of the curved edge of the apertures 126,136, 146 and 156, a different energy absorption curve results on a forcevs deflection graph of a vehicle impact. Specifically, the rates ofincrease in energy absorption can be controlled and more accuratelyadjusted while “tweaking” and fine-tuning the energy absorber 102.Substitution of different material blends in the energy absorber 102also can help.

In particular, it is noted that the end sections 180 and 181 of thepresent energy absorber 102 form integral box-shaped sections thatprovide a very consistent and strong corner impact strength. Thehoneycomb shape formed by ribs 160-163 and ribs 153 and 182 along withthe crescent-shaped flange 183 and the interaction of the end sections180-181 with the J-shaped section 110 of the mounting bracket 107 and108 and the end of the tube sections 104 and 105 of the bumper beam 101are important aspects of the present invention. Also, an importantinventive aspect is the concept of fine-tuning the energy absorber 102by changing wall thicknesses and providing apertures of different sizesto optimize a bumper system.

Yet another important feature of the present illustrated design of theenergy absorber 102 is shown by the offset 163A in lower wall 163, whichconnects the front and rear portions 163B and 163C of wall 163. Duringimpact, the front portion 163B telescopes overlappingly onto the rearportion 163C, with the offset 163A wrapping back upon itself and betweenthe portions 163B and 163C. This “wrapping” action provides high-energyabsorption and a very consistent and predictable collapse, which is verydesirable in energy absorbers.

The present invention is described as utilizing a B-shaped double-tubebumper beam that is rollformed and swept. The present B-shaped bumperbeam is sufficiently described herein for a person skilled in the art tounderstand and practice the present invention, but it is noted that theprocess and method of making the illustrated B-shaped bumper beam isdescribed in greater detail in Sturrus patent U.S. Pat. No. 5,454,504,if the reader desires such information. It is specifically contemplatedthat the present invention could be used in combination with a bumperbeam having a shallower channel instead of the deep channel illustrated.For example, the present invention would work on a D-shaped bumper wherethe bumper beam had a vertically-extending surface extending across asignificant vertical portion of a front face of the bumper beam but doesnot extend completely across a vertical front face of the bumper beam.On the merits, the teachings of U.S. Pat. No. 5,454,504 are incorporatedherein in its entirety for the purpose of providing a completedisclosure of the entire bumper system.

FURTHER EMBODIMENT

In regard to the illustrated preferred embodiment, a bumper system 320(FIGS. 26-31) for vehicles includes a bumper beam 321 and an energyabsorber 322 attached to a face of the bumper beam 321. The illustratedbeam is rollformed and swept (see Sturrus U.S. Pat. No. 5,454,504) andhas a continuous B-shaped double-tubular cross section (FIG. 27). Thedouble tubes are spaced vertically apart and include top and bottommid-walls 323 and 324 defining a longitudinally-extending channel 325along its rear surface. A polymeric energy absorber 322 has a lengthwith multiple box-shaped sections 327 (five box-shaped sections areshown, but not all are the same length) that abut the front surface 326of the bumper beam 321. The energy absorber 322 further includes aplurality of tying sections 328 that extend longitudinally between thebox-shaped sections 327 and also vertically between top and bottomportions 327 and 327″ of the box-shaped sections 327, as discussedbelow.

The B-shaped section of the bumper beam 321 (FIG. 28) includes, inaddition to top and bottom mid-walls 323 and 324, a top wall 334, a rearupper wall 335, a bottom wall 336, a rear lower wall 337, a primaryfront wall 338 and a channel-forming overlapping front wall 339. The toptube of the bumper beam 321 is formed by the walls 323, 334, 335, and338. The bottom tube of the bumper beam 321 is formed by the walls 324,336, 337, and 338. The top and bottom tubes are interconnected by frontwalls 338 and 339. Each of these walls 323-324 and 334-339 can be flator non-flat. For example, in some bumper systems (such as theillustrated bumper beam), it has been found to be beneficial to make thehorizontal walls 323, 324, 334, and 336 slightly bent or curved (in afront-to-rear direction), both for purposes of providing a bumper beamthat is less likely to prematurely kink and more likely to reliably andconsistently bend, but also for the purpose of ease of manufacture ofthe bumper beam. As illustrated, the mid-walls 323 and 324 include rearportions that are angled to created a tapered throat.

The energy absorber 322 is a molded component of non-foam polymer, suchas a blend of PC/ABS/TPE. For example, it is contemplated that GeneralElectric's XENOY polymer will work for this purpose. The energy absorber322 includes five box-shaped sections 327 that abut a front of the frontwall 338. Tying walls 328 hold the box-shaped sections 327 together. Theillustrated box-shaped sections 327 include top and bottom U-shapedsections 327′ and 327″. The top sections 327′ engaging the top of frontwall 338 are shaped slightly different (i.e. taller) than the bottomsections 327′ that engage the bottom of front wall 338, but it iscontemplated that they can be made similar in size and shape, ifdesired. The box-shaped sections 327 (FIG. 8A) each include a top wall341, a bottom wall 342, and opposing sidewalls 343 and 344. A flat frontwall 345 extends around walls 341-344 and forms a perimeter around them,tying the walls 341-344 together. Additionally, the box-shaped sections327 include a top wall 341A, a bottom wall 342A, and opposing end walls343A and 344A that extend from the outer edges of front wall 345 andextend parallel the walls 341-344, respectively. The U-shaped topsection 327′ is formed by walls 341 and 342, which form parallel legs,and by wall 345, which forms a vertical leg. The U-shaped section 327″is formed by walls 341A and 342A, which are parallel, and by verticalleg 345A. A rear wall 346 extends outwardly from the walls 341A-344Aforming a perimeter. The section 328 is that part of wall 346 thatinterconnects and ties adjacent box-like sections 327 together. Allwalls of sections 327 (and wall 328) are about 1.5 to 3.5 mm thick, ormore preferably about 2.0 mm to 2.5 mm thick. It is noted that the topand bottom walls 341, 341A, 342, 342A, when viewed from a position infront of the bumper system, can be wavy and undulating or otherwisenon-linear and non-flat in shape. The other walls can also be wavy orundulating. This provides the walls with increased strength forresisting buckling, and also helps eliminate distortions, such assnaking, that occur when molding a long part. It is also noted that thewalls 341, 341A, 342, and 342A extend longitudinally on the bumper beam321, but are discontinuous and further include non-blind surfaces toprevent die lock when molding. (i.e. This allows mold tooling to passthrough the plane of one wall to form another wall.) In other words, theenergy absorber 322 can be made by using male and female molds, neitherof which require secondary or movable die components for forming theenergy absorber 322.

The box-shaped sections 327 of the illustrated energy absorber 322 areable to absorb significant energy without failure, such as may beincurred in a low energy impact. Thus, in a low energy impact, theenergy absorber 322 absorbs the impact energy, and the bumper beam 321does not permanently or temporarily deform. In an intermediate energyimpact, the bumper beam 321 and the energy absorber 322 do deflect andabsorb energy, but do not permanently deform. However, the walls 323-324and 334-339 of the energy absorber 322 may permanently deform. In ahigh-energy impact, both the energy absorber 322 and the bumper beam 321initially absorb energy and then buckle as they approach a maximumamount of deflection. The point of buckling is designed into the bumpersystem 320 to cause a maximum amount of energy to be absorbed withoutdamaging the vehicle, while considering all relevant factors such asoccupant safety, government standards, and the like.

A top lip 353 extends rearwardly from the top of wall 346 of the boxsection 327, and a bottom lip 354 extends rearwardly from the bottom ofwall 346 of the box section 327. The lips 353 and 354 engage top andbottom surfaces on the bumper beam 321. Optionally, the lips 353 and 354can include attachment tabs or hooks (see hook tab 55 in FIG. 32 andhook tab 56 in FIG. 8) for engaging apertures or features in the bumperbeam 321 for retaining (temporarily or permanently) to the bumper beam321. These lips 353 and 354 are advantageous in that all (or most)fasteners can be eliminated for attaching the energy absorber 322 to thebumper beam 321. It is contemplated that the vehicle front fascia 357(FIG. 30) can be used to hold the energy absorber 322 on the bumper beam321 without any fasteners, if desired, as noted below.

It is noted that the present arrangement faces a “flat side” of theB-shaped cross section of the bumper beam 321 toward the energy absorber322, although it is contemplated that the present inventive energyabsorber 322 can be positioned against the lobed part of the B-shapedbumper beam 321 and function satisfactorily. In such case, the B-shapedbumper beam 321 would be swept with its “flat” face on the vehicle sideof the bumper beam and facing rearwardly.

In the present bumper system, the energy absorber 322 is relativelyloosely supported on the bumper beam 321. This is unusual in thathistorically, automobile manufacturers want the position of the energyabsorbers closely controlled and well-fastened to the bumper beam.However, testing has shown that a relatively loose energy absorber can,if properly designed, actually assist in preventing premature collapseof the energy absorber by allowing the energy absorber to adjust to theimpacting object to better “face” the impacting object as the impactcollision occurs.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent invention, and further it is to be understood that such conceptsare intended to be covered by the following claims unless these claimsby their language expressly state otherwise. Further, it is to beunderstood that methods related to the above concepts are believed to bewithin a scope of the present invention.

1. A bumper system for a passenger vehicle comprising: a beam having aface and adapted for attachment to a vehicle frame; and an energyabsorber supported against the face of the beam, the energy absorberincluding longitudinally-extending top and bottom horizontal walls, atleast part of one of the top and bottom horizontal walls including afront portion, a rear portion extending parallel the front portion, anda mid portion that interconnects the front and rear portions but thatoffsets and misaligns the front and rear portions so that, upon afrontal impact, the front and rear portions telescopingly collapse withthe offset mid portion wrapping back upon itself with a predictableenergy-absorbing collapse, wherein both of the top and bottom horizontalwalls include a front portion, a rear portion parallel the frontportion, and an offset mid portion that interconnects the front and rearportions but that offsets and misaligns the front and rear portions sothat, upon a frontal impact, the front and rear portions telescopinglycollapse with the offset mid portion wrapping back upon itself with apredictable energy-absorbing collapse.
 2. The bumper system defined inclaim 1, wherein the top and bottom horizontal walls include wavyundulations and are non-planar.
 3. The bumper system defined in claim 2,wherein the beam includes top and bottom beam walls, and wherein the topand bottom horizontal walls of the energy absorber generally align withthe top and bottom beam walls, respectively, such that impact energyfrom a crash is communicated directly from the energy absorber to thebeam.
 4. The bumper system defined in claim 3, wherein the energyabsorber includes flanges that extend overlappingly onto the top andbottom beam walls, the flanges including friction pads for frictionallyengaging the beam to temporarily retain the energy absorber on the beamduring assembly.
 5. A bumper system for a passenger vehicle comprising:a beam having a face and adapted for attachment to a vehicle frame; andan energy absorber supported against the face of the beam, the energyabsorber including longitudinally-extending top and bottom horizontalwalls, at least part of one of the top and bottom horizontal wallsincluding a front portion, a rear portion extending parallel the frontportion, and a mid portion that interconnects the front and rearportions but that offsets and misaligns the front and rear portions sothat, upon a frontal impact, the front and rear portions telescopinglycollapse with the offset mid portion wrapping back upon itself with apredictable energy-absorbing collapse, wherein the front face of thebeam includes apertures, and the energy absorber includes hooks thatextend into the apertures and that resiliently snap-attach to the beamfor temporarily holding the energy absorber on the beam.
 6. A bumpersystem for a passenger vehicle comprising: a beam having a face andadapted for attachment to a vehicle frame; and an energy absorbersupported against the face of the beam, the energy absorber includinglongitudinally-extending top and bottom horizontal walls, at least partof one of the top and bottom horizontal walls including a front portion,a rear portion extending parallel the front portion, and a mid portionthat interconnects the front and rear portions but that offsets andmisaligns the front and rear portions so that, upon a frontal impact,the front and rear portions telescopingly collapse with the offset midportion wrapping back upon itself with a predictable energy-absorbingcollapse, wherein the beam has top and bottom beam walls that generallyalign with the top and bottom horizontal walls of the energy absorber,and further the energy absorber including flanges that overlap onto thetop and bottom beam walls and that include at least a pair offingertip-shaped friction pads that frictionally engage the top andbottom beam walls to temporarily retain the energy absorber to the beam.7. The bumper system defined in claim 6, wherein the fingertip-shapedfriction pads engage top and bottom surfaces of the top and bottom beamwalls.
 8. The bumper system defined in claim 6, wherein the face of thebeam includes apertures, and the fingertip-shaped friction pads of theenergy absorber includes hooks that extend into the apertures and thatresiliently snap-attach to the beam for temporarily holding the energyabsorber on the beam.
 9. The bumper system defined in claim 6, whereinthe energy absorber includes a rear wall that engages the face of thebeam, and the flanges and fingertip-shaped friction pads extendrearwardly of the rear wall.
 10. The bumper system defined in claim 1,wherein the beam has front and rear beam walls; the front beam wallincluding at least one aperture in the front beam wall, with the rearbeam wall including a support area located behind and spaced from the atleast one aperture; and the energy absorber including front and rearwalls and at least one structural column extending from the front wallthrough the rear wall and through the at least one aperture in the frontbeam wall to a location near the support area on the rear beam wall,wherein the front wall of the energy absorber receives support from thefront beam wall via the structural column.
 11. The bumper system definedin claim 10, wherein the at least one aperture includes at least twoapertures, and wherein the at least one column includes at least twocolumns.
 12. The bumper system defined in claim 11, wherein the at leastone column defines a tubular shape.
 13. The bumper system defined inclaim 10, wherein the at least one column is configured to temporarilysupport the energy absorber on the beam.
 14. The bumper system definedin claim 10, wherein the at least one column defines a tubular shape.15. A bumper system for a passenger vehicle comprising: anenergy-absorbing beam adapted for connection to a vehicle for absorbingenergy during a vehicle crash, the beam having a face andlongitudinally-extending top and bottom beam walls; and an energyabsorber member abutting the face and also havinglongitudinally-extending top and bottom absorber walls; theenergy-absorbing beam and energy absorber member being constructed toconsistently and predictably absorb energy upon impact, including atleast one of the walls of the beam and energy absorber member having alongitudinally-elongated front portion, a parallellongitudinally-elongated rear portion, and a mid portion thatinterconnects the front and rear portions but that offsets and misalignsthe front and rear portions so that, upon a horizontal impact, the frontand rear portions telescopingly collapse with the offset mid portionwrapping back upon itself with a predictable energy absorber collapse,wherein the energy absorber member is made of polymeric material andextends a length of the beam.
 16. The bumper system defined in claim 15,wherein the energy absorber member includes the one wall having thefront and rear portions and the mid portion.
 17. The bumper systemdefined in claim 15, wherein the one wall having the mid portion extendsa length of the bumper system.
 18. The bumper system defined in claim15, wherein the bottom absorber wall includes the front and rearportions and the mid portion.
 19. The bumper system defined in claim 15,wherein the front and rear portions are linear and extend generallyalong parallel lines.
 20. An energy absorbing apparatus for a passengervehicle bumper system comprising: an energy absorbing component havinglongitudinally-extending top and bottom walls adapted to extend a widthof a passenger vehicle, at least one of the walls having alongitudinally-elongated front portion, a longitudinally-elongated rearportion, and a mid portion that interconnects the front and rearportions but that offsets and misaligns the front and rear portions sothat, upon a horizontal impact, the front and rear portionstelescopingly collapse with the offset mid portion wrapping back uponitself with a predictable energy absorbing collapse, wherein the energyabsorbing component is made from polymeric material.
 21. The energyabsorbing apparatus defined in claim 20, wherein the energy absorbingcomponent has a rear surface shaped to abut a bumper beam.
 22. Theenergy absorbing apparatus defined in claim 20, wherein only the bottomwall includes the front and rear portions and the mid portion.
 23. Theenergy absorbing apparatus defined in claim 20, wherein the front andrear portions are linear and extend generally along parallel lines.